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首页> 外文期刊>Applied Catalysis, B. Environmental: An International Journal Devoted to Catalytic Science and Its Applications >Zirconia-supported tungstophosphoric heteropolyacid as heterogeneous acid catalyst for biodiesel production
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Zirconia-supported tungstophosphoric heteropolyacid as heterogeneous acid catalyst for biodiesel production

机译：氧化锆支持的钨磷杂盐作为生物柴油生产的异烯酸催化剂

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A series of materials based on the immobilization of the 12-tungstophosphoric heteropolyacid over zirconia supports have been prepared and applied as heterogeneous acid catalysts in the esterification of palmitic acid with methanol as a model reaction for the preliminary stage of the biodiesel production. The title materials have been obtained through the sol-gel method combined with a subsequent hydrothermal treatment at mild conditions, which affords catalysts with larger porosity and higher thermal and chemical stability under the esterification reaction conditions than other preparative approaches. Generating the zirconia support by hydrolysis of an alkoxyde precursor in the presence of the heteropolyacid leads to materials with homogeneously well dispersed clusters, as well as to an increasing contribution of the tetragonal ZrO2 crystalline phase, a decreasing size of the nanoparticles and larger microporous volumes as the loading of the Keggin-type species increases. The 12-tungstophosphoric acid retains its catalytic activity in the esterification of palmitic acid with methanol at 60 degrees C upon immobilization over zirconia and conversions even higher than those observed under homogeneous conditions are obtained due to the active contribution of the support. The sample with a 30% mass percentage of heteropolyacid has been identified as the most efficient catalyst because it affords conversions above the 90% and shows the lower loss of activity over successive reaction runs among all of our materials. This loss of activity has been analyzed on the basis of the leaching of the catalyst and the fouling of the materials.
机译：已经制备了基于氧化锆载体的12〜钨磷杂酸的固定化的一系列材料，并在棕榈酸的酯化中与甲醇的酯化中的非均相酸催化剂作为模型反应，用于生物柴油生产的初步阶段。通过溶胶 - 凝胶法与随后的温和条件下的水热处理合并的标题材料，其在酯化反应条件下提供具有较大孔隙率和更高的热和化学稳定性的催化剂，而不是其它制备方法。通过在杂多酸的存在下通过水解烷氧基乙基前体产生氧化锆支持，导致具有均匀良好的分散的簇的材料，以及四边形ZrO2结晶相的贡献增加，纳米颗粒的减小和更大的微孔体积的贡献。 Keggin型物种的负载增加。 12-钨磷酸在固定在氧化锆上以60℃下甲醇的催化活性保留在棕榈酸的酯化中，并且由于载体的积极贡献，将甚至比在均匀条件下观察到的转化率。具有30％质量含量的杂多酸百分比的样品已被鉴定为最有效的催化剂，因为它提供高于90％的转化机，并且显示出在所有材料中连续反应的较低的活性损失。在催化剂的浸出和材料的污垢的基础上分析了这种活性丧失。

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